You can also implement hex encoding and decoding yourself, in case you want to avoid the dependency on the hex crate: use std::{fmt::Write, num::ParseIntError}; pub fn decode_hex(s: &str) -> Result<Vec<u8>, ParseIntError> { (0..s.len()) .step_by(2) .map(|i| u8::from_str_radix(&s[i..i + 2], 16)) .collect() } pub fn encode_hex(bytes: &[u8]) -> String { let mut s = String::with_capacity(bytes.len() * 2); … Read more
Since Rust 1.19 (cargo 0.20.0), thanks to https://github.com/rust-lang/cargo/pull/3929, you can now define a compile-time environment variable (env!(…)) for rustc and rustdoc via: println!(“cargo:rustc-env=KEY=value”); So OP’s program can be written as: // build.rs use std::process::Command; fn main() { // note: add error checking yourself. let output = Command::new(“git”).args(&[“rev-parse”, “HEAD”]).output().unwrap(); let git_hash = String::from_utf8(output.stdout).unwrap(); println!(“cargo:rustc-env=GIT_HASH={}”, git_hash); } … Read more
Here is an example implementation of the custom test framework solution mentioned by Masklinn: #![feature(custom_test_frameworks)] #![feature(test)] #![test_runner(custom_test_runner)] extern crate test; use test::{test_main_static, TestDescAndFn}; fn main() {} pub fn custom_test_runner(tests: &[&TestDescAndFn]) { println!(“Setup”); test_main_static(tests); println!(“Teardown”); } #[cfg(test)] mod tests { #[test] fn test1() { println!(“Test 1”) } #[test] fn test2() { println!(“Test 2”) } } This … Read more
None of the standard library collections maintain insertion order. You can instead use IndexMap from the indexmap crate, which preserves insertion order as long as you don’t call remove. use indexmap::indexmap; let map = indexmap! { “Z” => 1, “T” => 2, “R” => 3, “P” => 4, “K” => 5, “W” => 6, }; … Read more
Functions in Rust don’t capture variables from the surrounding environment, period. A “local” function in Rust is really just a global function that isn’t globally visible; it can’t do anything more than any other global function. Instead, Rust has closures which are distinct from functions in that they do capture variables from their environment. That … Read more
is there a way to do it without extracting their “inner” values every time with pattern matching, and without implementing the Add, Sub, … traits and overloading operators? No, the only way is to implement the traits manually. Rust doesn’t have an equivalent to the Haskell’s GHC extension GeneralizedNewtypeDeriving which allows deriving on wrapper types … Read more
If you want to remove elements, you can use retain(), which removes elements from the vector if the closure returns false: let mut vec = vec![1, 2, 3, 4]; vec.retain(|&x| x % 2 == 0); assert_eq!(vec, [2, 4]); If you want to modify the elements in place, you have to do that in a for … Read more
The Using Rust on Windows page you linked to dates from before rustup replaced the installer as the default option to install Rust. Installers are still available, but you should use rustup if possible, because it makes it easy to update and to use multiple toolchains at once (e.g. stable, beta and nightly). If you … Read more
Anything starting with & in Rust is a reference to a value, rather than a value itself. A &[u8] is a reference to a value which needs to exist elsewhere. Because you create the value it’s a reference to within the function, when the function returns, the value the reference points to no longer exists. … Read more
This doesn’t work because we can’t move s from &mut X. Then don’t do that… take the struct by value and return a new one: enum X { X1(String), X2(String), } fn increment_x(x: X) -> X { match x { X::X1(s) => X::X2(s), X::X2(s) => X::X1(s), } } Ultimately, the compiler is protecting you because … Read more